Escapement device



April 29, 1969 J. c. BERNEY 3,440,315

ESCAPEMENT DEVICE Filed Nov. 29, 1966 Sheet of 2 m m m i April 1969 J. c. BERNEY 3,440,815

ESCAPEMENT DEVICE Filed Nov. 29 1966 Sheet 2 0r 2 15 47 8 /q -m l :1 14

I 1 m 13 y L I l United States Patent 3,440,815 ESCAPEMENT DEVICE Jean Claude Berney, Lausanne, Switzerland, assignor to Bernard Golay S.A., Lausanne, Switzerland Filed Nov. 29, 1966, Ser. No. 597,727 Claims priority, application Switzerland, Dec. 7, 1965, 16,856/ 65 Int. Cl. G04b 15/06 U.S. Cl. 58116 9 Claims ABSTRACT OF THE DISCLOSURE This disclosure is concerned with an escapement assembly for a timepiece in which pallet arms are secured to the free extremity of a vibrator, the pallet arms having at their extremities gathering pallets cooperating with the teeth of the escapement wheel, these teeth having flanks and the active flank of each tooth being parallel to one of the faces of the corresponding pallet whereby the pallet arms can oscillate perpendicularly to the plane of the escapement wheel and the assembly can function satisfactorily in any position.

In a watch movement, the purpose of the escapement is to transmit the energy received by the gear train, itself driven by the driving spring to the regulating member formed by the spiral spring, and balance. This escapement comprises generally an independent pallet oscillating around an axis fixed in the plate. The mechanical linkage between the pallet and the regulating member consisting of the plate bearing the pin which stops against each of the horns of the pallet, is relatively complicated. Furthermore, the spiral spring balance assembly requires delicate adjustment.

Many decades ago it was thought possible to replace this system in a miniature clock, by a simpler construction comprising pallet arms in the shape of a half-circle, mounted at the extremity of a vibrating blade, encased in the plate, these pallet arms being provided with two gathering pallets diametrically opposed with respect to the centre of the escapement wheel. However, this solution, a derivative of the classic escapement, was never used since it did not lead to satisfactory results. In effect, the pallet arms requiring fairly considerable dimensions determined by the diameter of the escapement wheel, would have a mass too great with respect to the rigidity of the vibrating blade which cannot be selected of too large a size if one desires to obtain a sutficient amplitude of oscillation to ensure the good functioning of the escapement with the minimum expenditure of energy. There results inevitably an excessive buckling of the vibrating blade, according to the position of the escapement device, which makes impossible a practical application of the system.

The present invention precisely has for its object an escapement assembly for a watch movement comprising pallet arms rigid with a vibrator the vibration of which is kept up by the energy of the gear train and which cooperates with an escapement wheel, but made in such a way that the assembly functions satisfactorily in any posi tion.

This device is characterised by the fact that the pallet arms are disposed in such a way that they oscillate perpendicularly to the plane of the escapement wheel.

The annexed drawing represents by way of example one embodiment of the device according to the invention.

FIGURE 1 represents an escapement device with a vibrating blade.

FIGURE 2 shows a cross sectional view taken along 11-11 of FIGURE 3.

3,440,815 Patented Apr. 29, 1969 ice FIGURE 3 shows an exaggerated profile view of the escapement.

FIGURE 4 shows a modification of the device of FIG- URE 1.

FIGURE 5 is a cross-sectional view showing a further modification of the invention wherein the gathering pallets are shifted relatively to one another.

FIGURE 6 shows a further modification of the invention employing a second resonator as a time base.

Between plate 1 of the watch movement, represented in FIGURE 1 and a bridge 2 is pivoted an escapement wheel 3 the pinion of which 4 rigid with this wheel, meshes with a wheel 5, which may be the seconds wheel of a watch movement. In every case, wheel 5 transmits the energy of the driving member of the movement to the escapement wheel 3. This wheel 3 bears on its periphery two sets of teeth 6 and 7 cut on each of the opposite faces of wheel 3, the teeth of each of these sets being formed by a vertical side and an oblique side inclined in the direction corresponding to the direction of rotation indicated by arrow F of the escapement wheel. The sets of teeth 6 and 7 are furthermore displaced one with respect to the other by a length equal to a half tooth. The escapement wheel 3 cooperates with the pallet arms 8 which are small by comparison with the diameter of wheel 3 and disposed vertically. These pallet arms 8 bear two gathering pallets 9 and 10 formed by ruby stones, encased in each end of the pallet arms. These gathering pallets have when viewed profilewise (FIGURE 3) a vertical face 9a and 10a respectively and an oblique face 9b and 10b respectively, the two faces being respectively parallel to the flank 0f the teeth of each of the sets of teeth 6 and 7.

Pallet arms 8 are secured by encasing or by welding, to the extremity of the vibrating blade 12 encased by its extremity 12b in a rigid support formed by two blocks 13 and 14 gripping the blade by a pressure of pincers 15 guided by a column 16 and actuated by a screw 17. In order to increase the rigidity of the free end of the vibrating blade 12 in its oscillating plane, the extremity 12a of this blade is twisted by with respect to the rest of the blade, the small length of part 12a prevents practically the oscillation of the pallet arms in a plane parallel to the plate. Plate 1 has furthermore near the pallet arms, a hollow 11 surrounding the lower arm of pallet 8. The vertical dimension of this pallet accordingly is small.

The functioning of this escapement assembly can be seen clearly from FIGURES 2 and 3. Each of the gathering pallets 9 and 10 penetrate at rest very slightly in each of the corresponding sets of teeth 6 and 7. This penetration is indicated in the drawing by d. One tooth of one or the other of the sets of teeth will always then contact one of the flanks 9a or 10a of one of the gathering pallets. It is advantageous to maintain amplitude a of the oscillations of gathering pallets 9 and 10 at a minimal value by giving on the one hand to blade 12 a maximum rigidity rendering it insensitive to outer shocks and by additionally reducing its length. This amplitude is limited only by safety considerations bearing in mind probable wear of the end of the teeth of the sets of the teeth 6 and 7 and the mechanical stresses resulting from the shock between the end of these teeth and the edges of the gathering pallets. FIGURE 3 shows then the escapement device in its rest position in which each of gathering pallets 9 and 10 penetrate by a value d in sets of teeth 6 and 7. When wheel 3 driven by the driving member moves in the direction indicated by arrow F, the end of the inclined flank of tooth 18 hits against the end of face 10b of gathering pallet 10, communicating to the latter by a vertical component an impulse which drives the gathering pallets downwardly. Tooth 18 continues to move freely in the direction of arrow F and tooth 19 of the upper teeth 6 hits in its turn against face 9b of the upper gathering pallet 9, this gathering pallet retaining the escapement wheel 3 until the moment when the elastic return force of blade 12 drives gathering pallet 9 upwardly freeing tooth 19. The pressure of tooth 19 on the face 9b of gathering pallet 9 also has a vertical component through which is effected the transmission of energy from the escapement wheel to blade 12, necessary for the upkeep of the oscillation of the latter.

By a judicious choice of the inclination of the teeth it is possible to obtain a minimum transfer of energy suf ficing for the upkeep of the oscillation of the vibrating blade at its resonance frequency and ensuring a total dependency of the advance of wheel 3 on the oscillation of the vibrating blade at its resonance frequency.

In the example described, the time base is formed by the vibrating blade itself and it is therefore important that the frequency of oscillation be stable. In order to improve this stability, there could be used instead of a sirnple blade, a tuning fork or a resonator derived from a tuning fork, one of the branches bearing the pallet on and the other branch oscillating freely and synchronizing the first branch. There could also be used another form of resonator, for example a dynamically balanced resonator, such as a resonator in the shape of an H, O or S.

Furthermore instead of displacing one set of teeth with respect to the other set of teeth of the escapement wheel it is possible to displace one pallet a half tooth with respect to the other as shown in FIGURE 5.

It is very important to allow, with respect to pallet arms 8, to the escapement Wheel a certain clearance vertically and to provide for the possibility of regulating this clearance, a judicious choice thereof permitting to correct the buckling effect which might still exist in the escapement wheel.

The isochronism of such a system will never be particularly satisfactory so that as shown in FIGURE 6 it is preferred to use a second resonator (20) as a time base, the frequency of oscillation of which is a multiple of the oscillation frequency of the vibrating organ bearing the pallet arm and synchronizing the latter either mechanically, magnetically, electro-dynamically, or electro-magnetically. This second oscillator can be for example a tuning fork.

What is claimed is:

1. In a timepiece having a driving movement, a plate, a toothed escapement wheel pivoted on said plate and receiving driving energy from said movement, an escapement assembly comprising a vibrator having one extremity rigidly secured to said plate, and a free extremity, pallet arms rigidly secured to said free extremity and having at 5 these extremities thereof gathering pallets cooperating with the teeth of said escapement wheel, said teeth having flanks and one of said flanks being parallel to one side of the corresponding pallet whereby said pallet arms can oscillate perpendicularly to the plane of said escapement wheel and said assembly can function satisfactorily in any position.

2. Escapement assembly according to claim 1, wherein said vibrator constitutes at the same time the regulating member for said timepiece and said pallet arms are straight.

3. Escapement assembly according to claim 1, wherein said vibrator forms part of a resonator constituting a regulating member for said timepiece.

4. Escapement assembly according to claim 1, wherein said vibrator is a vibrating blade.

5. Assembly according to claim 1, having a resonator serving as a time base, said resonator oscillating at a frequency equal to a multiple of the frequency of said vibrator.

6. Assembly according to claim 1, wherein the escapement sides of said wheel each bear two sets of planar teeth cooperating each with a gathering pallet of the pallet.

7. Assembly according to claim 6, wherein the two sets of teeth are identical in shape and shifted one with respect to the other by a half tooth and that the gathering pallets are alined on a perpendicular to the plane of the escapement wheel.

8. Assembly according to claim 7, wherein said two sets of teeth are identical in shape and their teeth are alined while the gathering pallets are shifted one with respect to the other by a half tooth.

9. Assembly according to claim 1, wherein the free extremity of said vibrator bearing the pallet arms is twisted by with respect to the rest of the blade whereby the rigidity of said extremity is increased.

References Cited UNITED STATES PATENTS 765,678 7/ 1904 Reddohl 741.5 2,133,216 10/1938 Taliaferro 58117 2,373,429 4/ 1945 Straumann 58-116 2,475,730 7/1949 Wandrey 741.5 2,769,342 11/ 1956 Drouhot 74-1.5 2,924,102 2/ 1960 Drouhot 5 81 16 3,130,594 4/ 1964 Campbell 741.5 X

FOREIGN PATENTS 1,366,029 6/1964 France.

363,352 12/ 1931 Great Britain. 838,430 6/1960 Great Britain.

RICHARD B. WILKINSON, Primary Examiner. S. A. WAL, Assistant Examiner.

U .S. Cl. X.R. 74-1.5 

